Adipose tissue-selective ablation of ADAM10 results in divergent metabolic phenotypes following long-term dietary manipulation

A Disintegrin And Metalloproteinase domain-containing protein 10 (ADAM10), is involved in several metabolic and inflammatory pathways. We speculated that ADAM10 plays a modulatory role in adipose tissue inflammation and metabolism. To this end, we studied adipose tissue-specific ADAM10 knock-out mice (aKO). While young, regular chow diet-fed aKO mice showed increased insulin sensitivity, following prolonged (33 weeks) high-fat diet (HFD) exposure, aKO mice developed obesity and insulin resistance. Compared to controls, aKO mice showed less inflammatory adipokine profile despite the significant increase in adiposity. In brown adipose tissue, aKO mice on HFD had changes in CD8+ T cell populations indicating a lesser inflammatory pattern. Following HFD, both aKO and control littermates demonstrated decreased adipose tissue pro-inflammatory macrophages, and increased anti-inflammatory accumulation, without differences between the genotypes. Collectively, our observations indicate that selective deletion of ADAM10 in adipocytes results in a mitigated inflammatory response, leading to increased insulin sensitivity in young mice fed with regular diet. This state of insulin sensitivity, following prolonged HFD, facilitates energy storage resulting in increased fat accumulation which ultimately leads to the development of a phenotype of obesity and insulin resistance. In conclusion, the data indicate that ADAM10 has a modulatory effect of inflammation and whole-body energy metabolism.

Contribution of αβ T cells to macrophage polarization and MSC recruitment and proliferation on titanium implants

Physiochemical cues like topography and wettability can impact the inflammatory response and tissue integration after biomaterial implantation. T cells are essential for immunomodulation of innate immune cells and play an important role in the host response to biomaterial implantation. This study aimed to understand how CD4+ and CD8+ T cell subsets, members of the αβ T cell family, polarize in response to smooth, rough, or rough-hydrophilic titanium (Ti) implants and whether their presence modulates immune cell crosstalk and mesenchymal stem cell (MSC) recruitment following biomaterial implantation. Post-implantation in mice, we found that CD4+ and CD8+ T cell subsets polarized differentially in response to modified Ti surfaces. Additionally, mice lacking αβ T cells had significantly more pro-inflammatory macrophages, fewer anti-inflammatory macrophages, and reduced MSC recruitment in response to modified Ti post-implantation than αβ T cell -competent mice. Our results demonstrate that T cell activation plays a significant role during the inflammatory response to implanted biomaterials, contributing to macrophage polarization and MSC recruitment and proliferation, and the absence of αβ T cells compromises new bone formation at the implantation site. STATEMENT OF SIGNIFICANCE: T cells are essential for immunomodulation and play an important role in the host response to biomaterial implantation. Our results demonstrate that T cells actively participate during the inflammatory response to implanted biomaterials, controlling macrophage phenotype and recruitment of MSCs to the implantation site.

Fluoxetine restrains allergic inflammation by targeting an FcɛRI-ATP positive feedback loop in mast cells

There is a clinical need for new treatment options addressing allergic disease. Selective serotonin reuptake inhibitors (SSRIs) are a class of antidepressants that have anti-inflammatory properties. We tested the effects of the SSRI fluoxetine on IgE-induced function of mast cells, which are critical effectors of allergic inflammation. We showed that fluoxetine treatment of murine or human mast cells reduced IgE-mediated degranulation, cytokine production, and inflammatory lipid secretion, as well as signaling mediated by the mast cell activator ATP. In a mouse model of systemic anaphylaxis, fluoxetine reduced hypothermia and cytokine production. Fluoxetine was also effective in a model of allergic airway inflammation, where it reduced bronchial responsiveness and inflammation. These data show that fluoxetine suppresses mast cell activation by impeding an FcɛRI-ATP positive feedback loop and support the potential repurposing of this SSRI for use in allergic disease.

Inhibiting Isoprenylation Suppresses FcεRI-Mediated Mast Cell Function and Allergic Inflammation

IgE-mediated mast cell activation is a driving force in allergic disease in need of novel interventions. Statins, long used to lower serum cholesterol, have been shown in multiple large-cohort studies to reduce asthma severity. We previously found that statins inhibit IgE-induced mast cell function, but these effects varied widely among mouse strains and human donors, likely due to the upregulation of the statin target, 3-hydroxy-3-methylgutaryl-CoA reductase. Statin inhibition of mast cell function appeared to be mediated not by cholesterol reduction but by suppressing protein isoprenylation events that use cholesterol pathway intermediates. Therefore, we sought to circumvent statin resistance by targeting isoprenylation. Using genetic depletion of the isoprenylation enzymes farnesyltransferase and geranylgeranyl transferase 1 or their substrate K-Ras, we show a significant reduction in FcεRI-mediated degranulation and cytokine production. Furthermore, similar effects were observed with pharmacological inhibition with the dual farnesyltransferase and geranylgeranyl transferase 1 inhibitor FGTI-2734. Our data indicate that both transferases must be inhibited to reduce mast cell function and that K-Ras is a critical isoprenylation target. Importantly, FGTI-2734 was effective in vivo, suppressing mast cell-dependent anaphylaxis, allergic pulmonary inflammation, and airway hyperresponsiveness. Collectively, these findings suggest that K-Ras is among the isoprenylation substrates critical for FcεRI-induced mast cell function and reveal isoprenylation as a new means of targeting allergic disease.

Reduction of neutrophil extracellular traps accelerates inflammatory resolution and increases bone formation on titanium implants

Neutrophils are the most abundant immune cells in the blood and the first cells to be recruited to the biomaterial implantation site. Neutrophils are fundamental in recruiting mononuclear leukocytes to mount an immune response at the injury site. Neutrophils exert significant pro-inflammatory effects through the release of cytokines and chemokines, degranulation and release of myeloperoxidase (MPO) and neutrophil elastase (NE), and the production of large DNA-based networks called neutrophil extracellular traps (NETs). Neutrophils are initially recruited and activated by cytokines and pathogen- and damage-associated molecular patterns, but little is known about how the physicochemical composition of the biomaterial affects their activation. This study aimed to understand how ablating neutrophil mediators (MPO, NE, NETs) affected macrophage phenotype in vitro and osseointegration in vivo. We discovered that NET formation is a crucial mediator of pro-inflammatory macrophage activation, and inhibition of NET formation significantly suppresses macrophage pro-inflammatory phenotype. Furthermore, reducing NET formation accelerated the inflammatory phase of healing and produced greater bone formation around the implanted biomaterial, suggesting that NETs are essential regulators of biomaterial integration. Our findings emphasize the importance of the neutrophil response to implanted biomaterials and highlight innate immune cells' regulation and amplification signaling during the initiation and resolution of the inflammatory phase of biomaterial integration. STATEMENT OF SIGNIFICANCE: Neutrophils are the most abundant immune cells in blood and are the first to be recruited to the injury/implantation site where they exert significant pro-inflammatory effects. This study aimed to understand how ablating neutrophil mediators affected macrophage phenotype in vitro and bone apposition in vivo. We found that NET formation is a crucial mediator of pro-inflammatory macrophage activation. Reducing NET formation accelerated the inflammatory phase of healing and produced greater appositional bone formation around the implanted biomaterial, suggesting that NETs are essential regulators of biomaterial integration.

Neutrophil Elastase decreases SARS-CoV-2 Spike protein binding to human bronchial epithelia by clipping ACE-2 ectodomian from the epithelial surface

Patients with cystic fibrosis (CF) have decreased severity of SARS-CoV-2 infections, but the underlying cause is unknown. Patients with CF have high levels of neutrophil elastase (NE) in the airway. We examined whether respiratory epithelial angiotensin converting enzyme 2 (ACE-2), the receptor for the SARS-CoV-2 spike protein, is a proteolytic target of NE. Soluble ACE-2 (sACE-2) levels were quantified by ELISA in airway secretions and serum from patients with and without CF, and the association between sACE-2 levels and NE activity levels was evaluated in CF sputum. We determined that NE activity was directly correlated with increased ACE-2 in CF sputum. Additionally, primary human bronchial epithelial (HBE) cells, exposed to NE or control vehicle, were evaluated by western analysis for the release of cleaved ACE-2 ectodomain fragment into conditioned media, and by flow cytometry for the loss of cell surface ACE-2, its impact on SARS-CoV-2 spike protein binding. We found that NE treatment released ACE-2 ectodomain fragment from HBE and decreased spike protein binding to HBE. Furthermore, we performed NE treatment of recombinant ACE-2-Fc tagged protein in vitro to assess whether NE was sufficient to cleave recombinant ACE-2-Fc protein. Proteomic analysis identified, specific NE cleavage sites in the ACE-2 ectodomain that would result in loss of the putative N-terminal spike binding domain. Collectively, data support that NE plays a disruptive role in SARS-CoV-2 infection by catalyzing ACE-2 ectodomain shedding from the airway epithelia. This mechanism may reduce SARS-CoV-2 virus binding to respiratory epithelial cells and decrease severity of COVID19 infection.

Immune cell response to orthopedic and craniofacial biomaterials depends on biomaterial composition

Materials for craniofacial and orthopedic implants are commonly selected based on mechanical properties and corrosion resistance. The biocompatibility of these materials is typically assessed in vitro using cell lines, but little is known about the response of immune cells to these materials. This study aimed to evaluate the inflammatory and immune cell response to four common orthopedic materials [pure titanium (Ti), titanium alloy (TiAlV), 316L stainless steel (SS), polyetheretherketone (PEEK)]. Following implantation into mice, we found high recruitment of neutrophils, pro-inflammatory macrophages, and CD4+ T cells in response to PEEK and SS implants. Neutrophils produced higher levels of neutrophil elastase, myeloperoxidase, and neutrophil extracellular traps in vitro in response to PEEK and SS than neutrophils on Ti or TiAlV. Macrophages co-cultured on PEEK, SS, or TiAlV increased polarization of T cells towards Th1/Th17 subsets and decreased Th2/Treg polarization compared to Ti substrates. Although SS and PEEK are considered biocompatible materials, both induce a more robust inflammatory response than Ti or Ti alloy characterized by high infiltration of neutrophils and T cells, which may cause fibrous encapsulation of these materials. STATEMENT OF SIGNIFICANCE: Materials for craniofacial and orthopedic implants are commonly selected based on their mechanical properties and corrosion resistance. This study aimed to evaluate the immune cell response to four common orthopedic and craniofacial biomaterials: pure titanium, titanium-aluminum-vanadium alloy, 316L stainless steel, and PEEK. Our results demonstrate that while the biomaterials tested have been shown to be biocompatible and clinically successful, the inflammatory response is largely driven by chemical composition of the biomaterials.

Neutrophilia in severe asthma is reduced in Ormdl3 overexpressing mice

Genome-wide association studies have linked the ORM (yeast)-like protein isoform 3 (ORMDL3) to asthma severity. Although ORMDL3 is a member of a family that negatively regulates serine palmitoyltransferase (SPT) and thus biosynthesis of sphingolipids, it is still unclear whether ORMDL3 and altered sphingolipid synthesis are causally related to non-Th2 severe asthma associated with a predominant neutrophil inflammation and high interleukin-17 (IL-17) levels. Here, we examined the effects of ORMDL3 overexpression in a preclinical mouse model of allergic lung inflammation that is predominantly neutrophilic and recapitulates many of the clinical features of severe human asthma. ORMDL3 overexpression reduced lung and circulating levels of dihydrosphingosine, the product of SPT. However, the most prominent effect on sphingolipid levels was reduction of circulating S1P. The LPS/OVA challenge increased markers of Th17 inflammation with a predominant infiltration of neutrophils into the lung. A significant decrease of neutrophil infiltration was observed in the Ormdl3 transgenic mice challenged with LPS/OVA compared to the wild type and concomitant decrease in IL-17, that plays a key role in the pathogenesis of neutrophilic asthma. LPS decreased survival of murine neutrophils, which was prevented by co-treatment with S1P. Moreover, S1P potentiated LPS-induced chemotaxis of neutrophil, suggesting that S1P can regulate neutrophil survival and recruitment following LPS airway inflammation. Our findings reveal a novel connection between ORMDL3 overexpression, circulating levels of S1P, IL-17 and neutrophil recruitment into the lung, and questions the potential involvement of ORMDL3 in the pathology, leading to development of severe neutrophilic asthma.

Cellular inhibitor of apoptosis 2 (cIAP2) restricts neuroinflammation during experimental autoimmune encephalomyelitis

Background

Immune activation, neuroinflammation, and cell death are the hallmarks of multiple sclerosis (MS), which is an autoimmune demyelinating disease of the central nervous system (CNS). It is well-documented that the cellular inhibitor of apoptosis 2 (cIAP2) is induced by inflammatory stimuli and regulates adaptive and innate immune responses, cell death, and the production of inflammatory mediators. However, the impact of cIAP2 on neuroinflammation associated with MS and disease severity remains unknown.

Methods

We used experimental autoimmune encephalomyelitis (EAE), a widely used mouse model of MS, to assess the effect of cIAP2 deletion on disease outcomes. We performed a detailed analysis on the histological, cellular, and molecular levels. We generated and examined bone-marrow chimeras to identify the cIAP2-deficient cells that are critical to the disease outcomes.

Results

cIAP2^−/− mice exhibited increased EAE severity, increased CD4⁺ T cell infiltration, enhanced proinflammatory cytokine/chemokine expression, and augmented demyelination. This phenotype was driven by cIAP2-deficient non-hematopoietic cells. cIAP2 protected oligodendrocytes from cell death during EAE by limiting proliferation and activation of brain microglia. This protective role was likely exerted by cIAP2-mediated inhibition of the non-canonical NLRP3/caspase-8-dependent myeloid cell activation during EAE.

Conclusions

Our findings suggest that cIAP2 is needed to modulate neuroinflammation, cell death, and survival during EAE. Significantly, our data demonstrate the critical role of cIAP2 in limiting the activation of microglia during EAE, which could be explored for developing MS therapeutics in the future.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-022-02527-6.

Dissecting the Balance Between Metabolic and Oncogenic Functions of Astrocyte-Elevated Gene-1/Metadherin

Obesity is an enormous global health problem, and obesity-induced nonalcoholic steatohepatitis (NASH) is contributing to a rising incidence and mortality for hepatocellular carcinoma (HCC). Increase in de novo lipogenesis and decrease in fatty acid β-oxidation (FAO) underlie hepatic lipid accumulation in NASH. Astrocyte-elevated gene-1/metadherin (AEG-1) overexpression contributes to both NASH and HCC. AEG-1 harbors an LXXLL motif through which it blocks activation of peroxisome proliferator activated receptor α (PPARα), a key regulator of FAO. To better understand the role of LXXLL motif in mediating AEG-1 function, using clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 technology, we generated a mouse model (AEG-1-L24K/L25H) in which the LXXLL motif in AEG-1 was mutated to LXXKH. We observed increased activation of PPARα in AEG-1-L24K/L25H livers providing partial protection from high-fat diet-induced steatosis. Interestingly, even with equal gene dosage levels, compared with AEG-1-wild-type livers, AEG-1-L24K/L25H livers exhibited increase in levels of lipogenic enzymes, mitogenic activity and inflammation, which are attributes observed when AEG-1 is overexpressed. These findings indicate that while LXXLL motif favors steatotic activity of AEG-1, it keeps in check inflammatory and oncogenic functions, thus maintaining a homeostasis in AEG-1 function. AEG-1 is being increasingly appreciated as a viable target for ameliorating NASH and NASH-HCC, and as such, in-depth understanding of the functions and molecular attributes of this molecule is essential. Conclusion: The present study unravels the unique role of the LXXLL motif in mediating the balance between the metabolic and oncogenic functions of AEG-1.

Isolation of the Stromal Vascular Fraction from Adipose Tissue and Subsequent Differentiation into White or Beige Adipocytes

Non-alcoholic steatohepatitis (NASH) is linked to adipose tissue dysfunction, with weight loss being the only treatment shown to reverse it. Due to this correlation with obesity, the study of adipose tissue and adipocytes is an important step in understanding the pathogenesis of this disease. Here, we describe the isolation process of the stromal vascular fraction (SVF) of adipose tissue. The SVF contains the foundational cells that will differentiate into adipocytes. These cells can be isolated and subsequently differentiated in vitro into white and beige adipocytes. We outline the in vitro differentiation of pre-adipocytes into cultured white and beige adipocytes using both human and mouse adipose tissue.

Identification of the transgene insertion site for an adipocyte-specific adiponectin-cre model and characterization of the functional consequences

The Adipoq-Cre transgenic mouse is widely used in the development of adipocyte-specific genetic manipulations for the study of obesity and type 2 diabetes. In the process of developing a new mouse model utilizing the adipocyte selective Adipoq-Cre transgenic mouse, strong genetic linkage between a gene of interest, Adam10, and the Adipoq-Cre transgene was discovered. Whole-genome sequencing of the Adipoq-Cre transgenic mouse model identified the genomic insertion site within the Tbx18 gene locus on chromosome 9 and this insertion causes a significant decrease in Tbx18 gene expression in adipose tissue. Insertion of genes Kng2, Kng1, Eif4a2 and Rfc4 also occurred in the Adipoq-Cre transgenic mouse, and these passenger genes may have functional consequences in various tissues.

Extraction-free rapid cycle RT-qPCR and extreme RT-PCR for SARS-CoV-2 virus detection

Introduction/Objective

Since the start of the coronavirus disease 2019 (COVID-19) pandemic, molecular diagnostic testing for detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has faced substantial supply chain shortages and noteworthy delays in result reporting after sample collection. Supply chain shortages have been most evident in reagents for RNA extraction and rapid diagnostic testing. In this study, we explored the kinetic limitations of extraction-free rapid cycle RT-qPCR for SARS-CoV-2 virus detection using the commercially available capillary based LightCycler.

Methods/Case Report

We optimized reverse transcription and PCR under extraction-free and rapid thermocycling conditions utilizing hydrolysis probe-based detection methods using a Roche LightCycler.

Results (if a Case Study enter NA)

This protocol improves detection speed while maintaining the sensitivity and specificity of hydrolysis probe-based detection. Percentage agreement between the developed assay and previously tested positive patient samples was 97.6% (n= 40/41) and negative patient samples was 100% (40/40). We further demonstrate that using purified RNA, SARS-CoV-2 testing using extreme RT-PCR and product verification by melting can be completed in less than 3 minutes.

Conclusion

We developed a protocol for sensitive and specific RT-qPCR of SARS-CoV-2 RNA from nasopharyngeal swabs in less than 20 minutes, with minimal hands-on time requirements. Overall, these studies provide a framework for increasing the speed of SARS-CoV-2 and other infectious disease testing.

Extraction-Free Rapid Cycle Quantitative RT-PCR and Extreme RT-PCR for SARS-CoV-2 Virus Detection

Since the start of the coronavirus disease 2019 (COVID-19) pandemic, molecular diagnostic testing for detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has faced substantial supply chain shortages and noteworthy delays in result reporting after sample collection. Supply chain shortages have been most evident in reagents for RNA extraction and rapid diagnostic testing. This study explored the kinetic limitations of extraction-free rapid cycle quantitative real-time RT-PCR for SARS-CoV-2 virus detection using the commercially available capillary-based LightCycler. After optimizing for time and reaction conditions, a protocol for sensitive and specific quantitative RT-PCR of SARS-CoV-2 RNA from nasopharyngeal swabs in <20 minutes was developed, with minimal hands-on time requirements. This protocol improves detection speed while maintaining the sensitivity and specificity of hydrolysis probe-based detection. Percentage agreement between the developed assay and previously tested positive patient samples was 97.6% (n = 40/41), and negative patient samples was 100% (40/40). The study further demonstrates that using purified RNA, SARS-CoV-2 testing using extreme RT-PCR, and product verification by melting can be completed in <3 minutes. Overall, these studies provide a framework for increasing the speed of SARS-CoV-2 and other infectious disease testing.

Ceramide in apoptosis and oxidative stress in allergic inflammation and asthma

BACKGROUND

Nothing is known about the mechanisms by which increased ceramide levels in the lung contribute to allergic responses and asthma severity.

OBJECTIVE

We sought to investigate the functional role of ceramide in mouse models of allergic airway disease that recapitulate the cardinal clinical features of human allergic asthma.

METHODS

Allergic airway disease was induced in mice by repeated intranasal administration of house dust mite or the fungal allergen Alternaria alternata. Processes that can be regulated by ceramide and are important for severity of allergic asthma were correlated with ceramide levels measured by mass spectrometry.

RESULTS

Both allergens induced massive pulmonary apoptosis and also significantly increased reactive oxygen species in the lung. Prevention of increases in lung ceramide levels mitigated allergen-induced apoptosis, reactive oxygen species, and neutrophil infiltration. In contrast, dietary supplementation of the antioxidant α-tocopherol decreased reactive oxygen species but had no significant effects on elevation of ceramide level or apoptosis, indicating that the increases in lung ceramide levels in allergen-challenged mice are not mediated by oxidative stress. Moreover, specific ceramide species were altered in bronchoalveolar lavage fluid from patients with severe asthma compared with in bronchoalveolar lavage fluid from individuals without asthma.

CONCLUSION

Our data suggest that elevation of ceramide level after allergen challenge contributes to the apoptosis, reactive oxygen species generation, and neutrophilic infiltrate that characterize the severe asthmatic phenotype. Ceramide might be the trigger of formation of Creola bodies found in the sputum of patients with severe asthma and could be a biomarker to optimize diagnosis and to monitor and improve clinical outcomes in this disease.

Stat5B is required for IgE-Mediated mast cell function in vitro and in vivo

Mast cells are found primarily at interfaces with the external environment, where they provide protection from pathogens but also elicit allergic inflammation. Mast cell activation by antigen-induced aggregation of IgE bound to the high affinity receptor, FcεRI, is a critical factor leading to inflammation and bronchoconstriction. We previously found that Stat5 is activated by FcεRI and that Stat5B suppression decreased IgE-induced cytokine production in vitro, but in vivo responses have not been assessed. We now show that Stat5B-deficient (KO) mice have reduced responses to IgE-mediated anaphylaxis, despite normal mast cell tissue distribution. Similarly, Stat5B KO mast cells have diminished IgE-induced degranulation and cytokine secretion in vitro. These mice have elevated IgE production that is not correlated with an intrinsic B cell defect. The current work demonstrates that the Stat5B isoform is required for normal mast cell function and suggests it limits IgE production in vivo.

Adipocyte ADAM17 plays a limited role in metabolic inflammation

The role of ADAM17, its substrates, and its natural inhibitor has been well studied in the context of inflammation, including metabolic inflammation, with mixed results. Previous studies examining global Adam17 knockdown models and ADAM17 inhibition using overexpression of endogenous ADAM17 inhibitors have shown improved metabolic health and decreased metabolic inflammation. However, there have been no studies examining the role of adipocyte ADAM17 using in vivo models. In this study, we developed an adipocyte-specific Adam17 knockout model using Adipoq-Cre-expressing mice crossed with Adam17-floxed mice. Using this model, we show that loss of adipocyte ADAM17 plays no evident role in baseline metabolic responses. Surprisingly, in a state of metabolic stress using high-fat diet (HFD), we observed that adipocyte ADAM17 had little effect overall on the metabolic phenotype as well as inflammatory cell populations. Using whole-body metabolic phenotyping, we show that loss of ADAM17 has no effect on energy utilization both at a baseline state as well as following HFD. However, lastly, using high-parameter flow cytometry, we show that loss of adipocyte ADAM17 alters macrophage and eosinophil populations following HFD. Overall, the studies presented here give more insight into the role of ADAM17 in metabolic responses and metabolic inflammation, specifically in adipocytes.

T cell receptor signaling defines the fate and pathway of ICOS internalization

The role of the inducible costimulatory of T cells (ICOS) has been shown to be important for many different T cell outcomes and is indispensable for follicular helper T cell (T_FH) responses. Since its discovery, there have been several studies on the regulation of ICOS at a transcriptional level. However, the post-translational regulation of ICOS has not been well characterized. Here, we demonstrate that ICOS is internalized following ligation. We show that costimulation with CD3 results in differential internalization and fate than stimulation of ICOS alone. Additionally, we show that ICOS internalization is PI3K and clathrin mediated. The studies presented here not only increase the mechanistic understanding of ICOS post-translational regulation but also give insight into the potential mechanisms by which T cells expressing high affinity receptors may be preferentially chosen to become T_FH cells with increased ICOS levels.

Fluvastatin Induces Apoptosis in Primary and Transformed Mast Cells

Statin drugs are widely employed in the clinic to reduce serum cholesterol. Because of their hydroxymethylglutaryl coenzyme A reductase antagonism, statins also reduce isoprenyl lipids necessary for the membrane anchorage and signaling of small G-proteins in the Ras superfamily. We previously found that statins suppress immunoglobulin E (IgE)-mediated mast cell activation, suggesting these drugs might be useful in treating allergic disease. Although IgE-induced function is critical to allergic inflammation, mast cell proliferation and survival also impact atopic disease and mast cell neoplasia. In this study, we describe fluvastatin-mediated apoptosis in primary and transformed mast cells. An IC₅₀ was achieved between 0.8 and 3.5 μM in both cell types, concentrations similar to the reported fluvastatin serum C_max value. Apoptosis was correlated with reduced stem cell factor (SCF)-mediated signal transduction, mitochondrial dysfunction, and caspase activation. Complementing these data, we found that p53 deficiency or Bcl-2 overexpression reduced fluvastatin-induced apoptosis. We also noted evidence of cytoprotective autophagy in primary mast cells treated with fluvastatin. Finally, we found that intraperitoneal fluvastatin treatment reduced peritoneal mast cell numbers in vivo These findings offer insight into the mechanisms of mast cell survival and support the possible utility of statins in mast cell-associated allergic and neoplastic diseases. SIGNIFICANCE STATEMENT: Fluvastatin, a statin drug used to lower cholesterol, induces apoptosis in primary and transformed mast cells by antagonizing protein isoprenylation, effectively inhibiting stem cell factor (SCF)-induced survival signals. This drug may be an effective means of suppressing mast cell survival.

Targeting ADAM10 in Cancer and Autoimmunity

Generating inhibitors for A Disintegrin And Metalloproteinase 10 (ADAM10), a zinc-dependent protease, was heavily invested in by the pharmaceutical industry starting over 20 years ago. There has been much enthusiasm in basic research for these inhibitors, with a multitude of studies generating significant data, yet the clinical trials have not replicated the same results. ADAM10 is ubiquitously expressed and cleaves many important substrates such as Notch, PD-L1, EGFR/HER ligands, ICOS-L, TACI, and the "stress related molecules" MIC-A, MIC-B and ULBPs. This review goes through the most recent pre-clinical data with inhibitors as well as clinical data supporting the use of ADAM10 inhibitor use in cancer and autoimmunity. It additionally addresses how ADAM10 inhibitor therapy can be improved and if inhibitor therapy can be paired with other drug treatments to maximize effectiveness in various disease states. Finally, it examines the ADAM10 substrates that are important to each disease state and if any of these substrates or ADAM10 itself is a potential biomarker for disease.

The DNA methyltransferase inhibitor, guadecitabine, targets tumor-induced myelopoiesis and recovers T cell activity to slow tumor growth in combination with adoptive immunotherapy in a mouse model of breast cancer

Background

Myeloid derived suppressor cells (MDSCs) present a significant obstacle to cancer immunotherapy because they dampen anti-tumor cytotoxic T cell responses. Previous groups, including our own, have reported on the myelo-depletive effects of certain chemotherapy agents. We have shown previously that decitabine increased tumor cell Class I and tumor antigen expression, increased ability of tumor cells to stimulate T lymphocytes, depleted tumor-induced MDSC in vivo and augmented immunotherapy of a murine mammary carcinoma.

Results

In this study, we expand upon this observation by testing a next-generation DNA methyltransferase inhibitor (DNMTi), guadecitabine, which has increased stability in the circulation. Using the 4 T1 murine mammary carcinoma model, in BALB/cJ female mice, we found that guadecitabine significantly reduces tumor burden in a T cell-dependent manner by preventing excessive myeloid proliferation and systemic accumulation of MDSC. The remaining MDSC were shifted to an antigen-presenting phenotype. Building upon our previous publication, we show that guadecitabine enhances the therapeutic effect of adoptively transferred antigen-experienced lymphocytes to diminish tumor growth and improve overall survival. We also show guadecitabine’s versatility with similar tumor reduction and augmentation of immunotherapy in the C57BL/6 J E0771 murine breast cancer model.

Conclusions

Guadecitabine depleted and altered MDSC, inhibited growth of two different murine mammary carcinomas in vivo, and augmented immunotherapeutic efficacy. Based on these findings, we believe the immune-modulatory effects of guadecitabine can help rescue anti-tumor immune response and contribute to the overall effectiveness of current cancer immunotherapies.

Binding of Host Cell Surface Protein Disulfide Isomerase by Anaplasma phagocytophilum Asp14 Enables Pathogen Infection

Diverse intracellular pathogens rely on eukaryotic cell surface disulfide reductases to invade host cells. Pharmacologic inhibition of these enzymes is cytotoxic, making it impractical for treatment. Identifying and mechanistically dissecting microbial proteins that co-opt surface reductases could reveal novel targets for disrupting this common infection strategy. Anaplasma phagocytophilum invades neutrophils by an incompletely defined mechanism to cause the potentially fatal disease granulocytic anaplasmosis. The bacterium's adhesin, Asp14, contributes to invasion by virtue of its C terminus engaging an unknown receptor. Yeast-two hybrid analysis identified protein disulfide isomerase (PDI) as an Asp14 binding partner. Coimmunoprecipitation confirmed the interaction and validated it to be Asp14 C terminus dependent. PDI knockdown and antibody-mediated inhibition of PDI reductase activity impaired A. phagocytophilum infection of but not binding to host cells. Infection during PDI inhibition was rescued when the bacterial but not host cell surface disulfide bonds were chemically reduced with tris(2-carboxyethyl)phosphine-HCl (TCEP). TCEP also restored bacterial infectivity in the presence of an Asp14 C terminus blocking antibody that otherwise inhibits infection. A. phagocytophilum failed to productively infect myeloid-specific-PDI conditional-knockout mice, marking the first demonstration of in vivo microbial dependency on PDI for infection. Mutational analyses identified the Asp14 C-terminal residues that are critical for binding PDI. Thus, Asp14 binds and brings PDI proximal to A. phagocytophilum surface disulfide bonds that it reduces, which enables cellular and in vivo infection.IMPORTANCEAnaplasma phagocytophilum infects neutrophils to cause granulocytic anaplasmosis, an emerging potentially fatal disease and the second-most common tick-borne illness in the United States. Treatment options are limited, and no vaccine exists. Due to the bacterium's obligatory intracellular lifestyle, A. phagocytophilum survival and pathogenesis are predicated on its ability to enter host cells. Understanding its invasion mechanism will yield new targets for preventing bacterial entry and, hence, disease. We report a novel entry pathway in which the A. phagocytophilum outer membrane protein Asp14 binds host cell surface protein disulfide isomerase via specific C-terminal residues to promote reduction of bacterial surface disulfide bonds, which is critical for cellular invasion and productive infection in vivo Targeting the Asp14 C terminus could be used to prevent/treat granulocytic anaplasmosis. Our findings have broad implications, as a thematically similar approach could be applied to block infection by other intracellular microbes that exploit cell surface reductases.

B cell ADAM17 controls T cell independent humoral immune responses through regulation of TACI and CD138

ADAM17 is known to contribute to the immune system through its shedding of tumor necrosis factor alpha (TNFα). However, the role of ADAM17 in B cell biology is not well characterized. To determine whether B cell ADAM17 contributes to T cell-independent humoral immune responses, we crossed CD19 Cre transgenic mice with mice bearing a floxed allele of ADAM17 (ADAM17^CD19). In this study, we show a B cell intrinsic role for ADAM17 in regulating marginal zone B cell (MZB) numbers in mice. Interestingly, we demonstrate that the loss of B cell ADAM17 results in reduced MZB numbers in the naïve state and after immunization with T-independent antigen, yet enhanced humoral immunity to T cell independent antigens. We additionally find elevated TACI and CD138 levels on plasma cells following immunization in ADAM17^CD19 mice. Overall, these findings suggest that B cell ADAM17 may orchestrate T independent immune responses through both MZB numbers and plasma cell antibody production.

The Il9 CNS-25 Regulatory Element Controls Mast Cell and Basophil IL-9 Production

IL-9 is an important mediator of allergic disease that is critical for mast cell-driven diseases. IL-9 is produced by many cell types, including T cells, basophils, and mast cells. Yet, how IL-9 is regulated in mast cells or basophils is not well characterized. In this report, we tested the effects of deficiency of a mouse Il9 gene regulatory element (Il9 CNS-25) in these cells in vivo and in vitro. In mast cells stimulated with IL-3 and IL-33, the Il9 CNS-25 enhancer is a potent regulator of mast cell Il9 gene transcription and epigenetic modification at the Il9 locus. Our data show preferential binding of STAT5 and GATA1 to CNS-25 over the Il9 promoter in mast cells and that T cells and mast cells have differing requirements for the induction of IL-9 production. Il9 CNS-25 is required for IL-9 production from T cells, basophils, and mast cells in a food allergy model, and deficiency in IL-9 expression results in decreased mast cell expansion. In a Nippostrongylus brasiliensis infection model, we observed a similar decrease in mast cell accumulation. Although decreased mast cells correlated with higher parasite egg burden and delayed clearance in vivo, T cell deficiency in IL-9 also likely contributes to the phenotype. Thus, our data demonstrate IL-9 production in mast cells and basophils in vivo requires Il9 CNS-25, and that Il9 CNS-25-dependent IL-9 production is required for mast cell expansion during allergic intestinal inflammation.

B1 Cell IgE Impedes Mast Cell-Mediated Enhancement of Parasite Expulsion through B2 IgE Blockade

Helminth infection is known for generating large amounts of poly-specific IgE. Here we demonstrate that innate-like B1 cells are responsible for this IgE production during infection with the nematode parasites Nippostrongylus brasiliensis and Heligmosomoides polygyrus bakeri. In vitro analysis of B1 cell immunoglobulin class switch recombination to IgE demonstrated a requirement for anti-CD40 and IL-4 that was further enhanced when IL-5 was added or when the B1 source was helminth infected mice. An IL-25-induced upregulation of IgE in B1 cells was also demonstrated. In T cell-reconstituted RAG1^−/− mice, N. brasiliensis clearance was enhanced with the addition of B2 cells in an IgE-dependent manner. This enhanced clearance was impeded by reconstitution with IgE sufficient B1 cells. Mucosal mast cells mediated the B2 cell enhancement of clearance in the absence of B1 cells. The data support B1 cell IgE secretion as a regulatory response exploited by the helminth.

A new look at IgE beyond allergies

Immunoglobulin E (IgE), though constitutively present at low levels, is most commonly studied in atopic disease where it plays a vital role in mast cell degranulation and in initiating a T helper 2 (Th2) response. With the advent of better detection assays, however, researchers are discovering the importance of IgE in actively contributing to many disease states and pathologies. This review will discuss the latest findings in IgE beyond its role in allergies and recently discovered roles for IgE in its cell-bound form on FcεRI-expressing effector cells like monocytes and dendritic cells. In terms of parasites, we will discuss helminth-induced IgE that appears to protect the worms from immune recognition and a tick-borne illness that elicits an IgE response against red meat. Next, we describe recent findings of how auto-reactive IgE can contribute to the progression of lupus and induce organ damage. Finally, we summarize the emerging roles of IgE in tumor surveillance and antibody-dependent cytotoxicity. We additionally discuss recent or ongoing clinical trials that either target harmful IgE or use the unique characteristics of the isotype.

Functional inhibition of acid sphingomyelinase disrupts infection by intracellular bacterial pathogens

Intracellular bacteria that live in host cell-derived vacuoles are significant causes of human disease. Parasitism of low-density lipoprotein (LDL) cholesterol is essential for many vacuole-adapted bacteria. Acid sphingomyelinase (ASM) influences LDL cholesterol egress from the lysosome. Using functional inhibitors of ASM (FIASMAs), we show that ASM activity is key for infection cycles of vacuole-adapted bacteria that target cholesterol trafficking-Anaplasma phagocytophilum, Coxiella burnetii, Chlamydia trachomatis, and Chlamydia pneumoniae. Vacuole maturation, replication, and infectious progeny generation by A. phagocytophilum, which exclusively hijacks LDL cholesterol, are halted and C. burnetii, for which lysosomal cholesterol accumulation is bactericidal, is killed by FIASMAs. Infection cycles of Chlamydiae, which hijack LDL cholesterol and other lipid sources, are suppressed but less so than A. phagocytophilum or C. burnetii A. phagocytophilum fails to productively infect ASM-/- or FIASMA-treated mice. These findings establish the importance of ASM for infection by intracellular bacteria and identify FIASMAs as potential host-directed therapies for diseases caused by pathogens that manipulate LDL cholesterol.

B Cell ADAM10 Controls Murine Lupus Progression through Regulation of the ICOS:ICOS Ligand Axis

The role of ICOS and its ligand (ICOSL) have both been shown to be essential for proper humoral responses as well as autoimmune Ab development in mouse models of lupus. In this paper, we report a specific role for the metalloprotease ADAM10 on B cells in regulating both ICOSL and ICOS in a mouse model of increased humoral immunity using B6^mir146a-/- mice and a model of lymphoproliferative disease using the well-characterized lpr model. B6^lpr mice lacking ADAM10 on B cells (A10B^lpr) have decreased nodal proliferation and T cell accumulation compared with control B6^lpr mice. Additionally, A10B^lpr mice have a drastic reduction in autoimmune anti-dsDNA Ab production. In line with this, we found a significant reduction in follicular helper T cells and germinal center B cells in these mice. We also show that lymphoproliferation in this model is closely tied to elevated ICOS levels and decreased ICOSL levels. Overall, our data not only show a role of B cell ADAM10 in control autoimmunity but also increase our understanding of the regulation of ICOS and ICOSL in the context of autoimmunity.

ADAM10-Mediated ICOS Ligand Shedding on B Cells Is Necessary for Proper T Cell ICOS Regulation and T Follicular Helper Responses

The proper regulation of ICOS and ICOS ligand (ICOSL) has been shown to be essential for maintaining proper immune homeostasis. Loss of either protein results in defective humoral immunity, and overexpression of ICOS results in aberrant Ab production resembling lupus. How ICOSL is regulated in response to ICOS interaction is still unclear. We demonstrate that a disintegrin and metalloproteinase (ADAM)10 is the primary physiological sheddase of ICOSL in mice and humans. Using an in vivo system in which ADAM10 is deleted only on B cells, elevated levels of ICOSL were seen. This increase is also seen when ADAM10 is deleted from human B cell lines. Identification of the primary sheddase has allowed the characterization of a novel mechanism of ICOS regulation. In wild-type mice, interaction of ICOS/ICOSL results in ADAM10-induced shedding of ICOSL on B cells and moderate ICOS internalization on T cells. When this shedding is blocked, excessive ICOS internalization occurs. This results in severe defects in T follicular helper development and TH2 polarization, as seen in a house dust mite exposure model. In addition, enhanced TH1 and TH17 immune responses are seen in experimental autoimmune encephalomyelitis. Blockade of ICOSL rescues T cell ICOS surface expression and rescues, at least in part, T follicular helper numbers and the abnormal Ab production previously reported in these mice. Overall, we propose a novel regulation of the ICOS/ICOSL axis, with ADAM10 playing a direct role in regulating ICOSL, as well as indirectly regulating ICOS, thus controlling ICOS/ICOSL-dependent responses.

Macrophage migration inhibitory factor deficiency enhances immune response to Nippostrongylus brasiliensis

Infections with helminth parasites are endemic in the developing world and are a target for intervention with new therapies. Macrophage migration inhibitory factor (MIF) is a cytokine with pleiotropic effects in inflammation and immune responses. We investigated the role of MIF in a naturally cleared model of helminth infection in rodents, Nippostrongylus brasiliensis. At day 7 postinfection, MIF-deficient (MIF^-/-) mice had reduced parasite burden and mounted an enhanced type 2 immune response (Th2), including increased Gata3 expression and interleukin-13 (IL-13) production in the mesenteric lymph nodes (MLNs). Bone marrow reconstitution demonstrated that MIF produced from hematopoietic cells was crucial and Rag1^-/- reconstitution provided direct evidence that MIF^-/- CD4⁺ T cells were responsible for the augmented parasite clearance. MIF^-/- CD4⁺ T cells produced less IL-6 postinfection, which correlated with enhanced Th2 responses. MIF^-/- CD4⁺ T cells exhibited lower nuclear factor-κB activation, potentially explaining the reduction in IL-6. Finally, we demonstrated enhanced clearance of the parasite and Th2 response in wild-type mice treated with the MIF tautomerase inhibitor, sulforaphane, a compound found naturally found in cruciferous vegetables. These results are the first to describe the importance of the tautomerase enzyme activity in MIF function in N. brasiliensis infection.

Multiple Bone Lesions in an 8-Month-Old Child Presenting with Pathologic Fracture: A Rare Case of Solely Osseous Multicentric Infantile Myofibromatosis

CASE

An otherwise healthy 8-month-old boy presented with a pathologic fracture of the distal aspect of the radius. Further work-up demonstrated widespread osseous lesions of the axial and the appendicular skeleton with no soft-tissue or visceral involvement.

CONCLUSION

Infantile myofibromatosis has a spectrum of severity that demands a careful and complete work-up. In rare cases such as the present one, it can manifest as multiple osseous lesions. The patient in the present case was managed conservatively, with no morbidity demonstrated at 1 year of follow-up.

Antigen transfer from exosomes to dendritic cells as an explanation for the immune enhancement seen by IgE immune complexes

IgE antigen complexes induce increased specific T cell proliferation and increased specific IgG production. Immediately after immunization, CD23⁺ B cells capture IgE antigen complexes, transport them to the spleen where, via unknown mechanisms, dendritic cells capture the antigen and present it to T cells. CD23, the low affinity IgE receptor, binds IgE antigen complexes and internalizes them. In this study, we show that these complexes are processed onto B-cell derived exosomes (bexosomes) in a CD23 dependent manner. The bexosomes carry CD23, IgE and MHC II and stimulate antigen specific T-cell proliferation in vitro. When IgE antigen complex stimulated bexosomes are incubated with dendritic cells, dendritic cells induce specific T-cell proliferation in vivo, similar to IgE antigen complexes. This suggests that bexosomes can provide the essential transfer mechanism for IgE antigen complexes from B cells to dendritic cells.

Mast cell histamine promotes the immunoregulatory activity of myeloid-derived suppressor cells

It has been shown recently that MCs are required for differential regulation of the immune response by granulocytic versus monocytic MDSCs. Granulocytic MDSCs promoted parasite clearance, whereas monocytic MDSCs enhanced tumor progression; both activities were abrogated in MC-deficient mice. Herein, we demonstrate that the lack of MCs also influences MDSC trafficking. Preferential trafficking to the liver was not seen in MC-deficient mice. In addition, evidence that the MC mediator histamine was important in MDSC trafficking and activation is also shown. MDSCs express HR1-3. Blockade of these receptors by HR1 or HR2 antagonists reversed the histamine enhancement of MDSC survival and proliferation observed in cell culture. In addition, histamine differentially influenced Arg1 and iNOS gene expression in MDSCs and greatly enhanced IL-4 and IL-13 message, especially in granulocytic MDSCs. Evidence that histamine influenced activity seen in vitro translated to in vivo when HR1 and HR2 antagonists blocked the effect of MDSCs on parasite expulsion and tumor metastasis. All of these data support the MDSC-mediated promotion of Th2 immunity, leading to the suggestion that allergic-prone individuals would have elevated MDSC levels. This was directly demonstrated by looking at the relative MDSC levels in allergic versus control patients. Monocytic MDSCs trended higher, whereas granulocytic MDSCs were increased significantly in allergic patients. Taken together, our studies indicate that MCs and MC-released histamine are critical for MDSC-mediated immune regulation, and this interaction should be taken into consideration for therapeutic interventions that target MDSCs.

Myeloid-derived suppressor cells enhance IgE-mediated mast cell responses

Mast cells and MDSCs are increased by parasitic infection and tumor growth. We previously demonstrated that enhanced MDSC development in ADAM10 transgenic mice yielded resistance to Nb infection and that coculturing MDSCs and mast cells enhanced cytokine production. In the current work, we show that MDSC-mast cell coculture selectively enhances IgE-mediated cytokine secretion among mast cells, without increasing MDSC cytokine production. This effect was independent of cell contact and elicited by Ly6C(+) and Ly6C/G+ MDSC subsets. These interactions were functionally important. MDSC depletion with the FDA-approved drug gemcitabine exacerbated Nb or Trichinella spiralis infection and reduced mast cell-dependent AHR and lung inflammation. Adoptive transfer of MDSC worsened AHR in WT but not mast cell-deficient Wsh/Wsh mice. These data support the hypothesis that MDSCs enhance mast cell inflammatory responses and demonstrate that this interaction can be altered by an existing chemotherapeutic.

Cutting edge: mast cells critically augment myeloid-derived suppressor cell activity

Myeloid-derived suppressor cells (MDSCs) are primarily recognized for their immunosuppressive properties in malignant disease. However, their interaction with other innate immune cells and their regulation of immune responses, such as in parasitic infection, necessitate further characterization. We used our previously published mouse model of MDSC accumulation to examine the immunoregulatory role of MDSCs in B16 melanoma metastasis and Nippostrongylus brasiliensis infection. In this study, we demonstrate that the activity of MDSCs is dependent on the immune stimuli and subset induced. Monocytic MDSCs predictably suppressed antitumor immune responses but granulocytic MDSCs surprisingly enhanced the clearance of N. brasiliensis infection. Intriguingly, both results were dependent on MDSC interaction with mast cells (MCs), as demonstrated by adoptive-transfer studies in MC-deficient (Kit(Wsh)(/)(Wsh)) mice. These findings were further supported by ex vivo cocultures of MCs and MDSCs, indicating a synergistic increase in cytokine production. Thus, MCs can enhance both immunosuppressive and immunosupportive functions of MDSCs.

A disintegrin and metalloproteinase 10 regulates antibody production and maintenance of lymphoid architecture

A disintegrin and metalloproteinase 10 (ADAM10) is a zinc-dependent proteinase related to matrix metalloproteinases. ADAM10 has emerged as a key regulator of cellular processes by cleaving and shedding extracellular domains of multiple transmembrane receptors and ligands. We have developed B cell-specific ADAM10-deficient mice (ADAM10(B-/-)). In this study, we show that ADAM10 levels are significantly enhanced on germinal center B cells. Moreover, ADAM10(B-/-) mice had severely diminished primary and secondary responses after T-dependent immunization. ADAM10(B-/-) displayed impaired germinal center formation, had fewer follicular Th cells, decreased follicular dendritic cell networks, and altered chemokine expression in draining lymph nodes (LNs). Interestingly, when spleen and LN structures from immunized mice were analyzed for B and T cell localization, tissues structure was aberrant in ADAM10(B-/-) mice. Importantly, when ADAM10-deficient B cells were stimulated in vitro, they produced comparable Ab as wild type B cells. This result demonstrates that the defects in humoral responses in vivo result from inadequate B cell activation, likely because of the decrease in follicular Th cells and the changes in structure. Thus, ADAM10 is essential for the maintenance of lymphoid structure after Ag challenge.

Identification of the novel HLA-C allele Cw*0751

We report the novel HLA-Cw allele HLA-Cw*0751. The allele was identified during routine sequence-based typing in our laboratory. The novel allele is identical to Cw*07020101 except for a single nucleotide change in codon 90.2 in position 268. HLA-Cw*0751 allele possesses an adenine at position 268 in exon 2, while HLA-Cw*07020101 has a cytosine at this position. Although this substitution does not change serologic reactivity of HLA-Cw7 molecule, it changes the amino acid at codon 90 from an aspartic acid to an alanine. Aspartic acid is polar and acidic, while alanine is non-polar and neutral.

Centaurin β4 in cancer

Centaurin beta4 proteins are products of the DDEF1 (development and differentiation-enhancing factor 1) locus on human chromosome 8q24.1-24.2. Recent reports have indicated that this region and its products are amplified during development of several human cancers. Centaurins are GAPs (GTPase-activating proteins) that, together with GEFs (guanine nucleotide-exchange factors), regulate cyclic activation of Arfs (ADP-ribosylation factors), members of the Ras GTPase superfamily. Centaurin beta4 proteins associate with a variety of cellular signalling components implicated in control of growth, survival and movement and may act to direct assembly and/or disassembly of molecular complexes in concert with Arf, lipid and protein phosphorylation signalling pathways.

Who should manage continuous renal replacement in the intensive care setting? A nursing viewpoint

Since its inception, continuous renal replacement therapy (CRRT) has been performed in critical care units with or without the involvement of nephrology nursing support (1,2). It is apparent that the issue of providing care to patients requiring this therapy is not so much a debate on the nursing control of CRRT, but a focused discussion on the nursing management and delivery of care to the patient receiving CRRT in the intensive care setting. Although the choice of a nursing care model for CRRT is dependent on many clinical and organisational factors, the use of one nursing specialty to deliver CRRT care can leave gaps in practice. The Joint or Collaborative Nephrology/critical care nursing model brings the highest level of nursing expertise to the bedside. The joint model tends to promote collaboration between two distinct nursing specialties, with opportunities for setting joint standards and promoting research. With this in mind, this discussion will examine some of the factors affecting structuring of nursing care, describe nursing models currently in use, compare the attributes of each, and conclude which model is preferred for the delivery of nursing care for CRRT.

Serial analysis of gene expression (SAGE) in Plasmodium falciparum: application of the technique to A-T rich genomes

The advent of high-throughput methods for the analysis of global gene expression, together with the Malaria Genome Project open up new opportunities for furthering our understanding of the fundamental biology and virulence of the malaria parasite. Serial analysis of gene expression (SAGE) is particularly well suited for malarial systems, as the genomes of Plasmodium species remain to be fully annotated. By simultaneously and quantitatively analyzing mRNA transcript profiles from a given cell population, SAGE allows for the discovery of new genes. In this study, one reports the successful application of SAGE in Plasmodium falciparum, 3D7 strain parasites, from which a preliminary library of 6880 tags corresponding to 4146 different genes was generated. It was demonstrated that P. falciparum is amenable to this technique, despite the remarkably high A-T content of its genome. SAGE tags as short as 10 nucleotides were sufficient to uniquely identify parasite transcripts from both nuclear and mitochondrial genomes. Moreover, the skewed A-T content of parasite sequence did not preclude the use of enzymes that are crucial for generating representative SAGE libraries. Finally, a few modifications to DNA extraction and cloning steps of the SAGE protocol proved useful for circumventing specific problems presented by A-T rich genomes.

Co-ordinated programme of gene expression during asexual intraerythrocytic development of the human malaria parasite Plasmodium falciparum revealed by microarray analysis

Plasmodium falciparum is a protozoan parasite responsible for the most severe forms of human malaria. All the clinical symptoms and pathological changes seen during human infection are caused by the asexual blood stages of Plasmodium. Within host red blood cells, the parasite undergoes enormous developmental changes during its maturation. In order to analyse the expression of genes during intraerythrocytic development, DNA microarrays were constructed and probed with stage-specific cDNA. Developmental upregulation of specific mRNAs was found to cluster into functional groups and revealed a co-ordinated programme of gene expression. Those involved in protein synthesis (ribosomal proteins, translation factors) peaked early in development, followed by those involved in metabolism, most dramatically glycolysis genes. Adhesion/invasion genes were turned on later in the maturation process. At the end of intraerythrocytic development (late schizogony), there was a general shut-off of gene expression, although a small set of genes, including a number of protein kinases, were turned on at this stage. Nearly all genes showed some regulation over the course of development. A handful of genes remained constant and should be useful for normalizing mRNA levels between stages. These data will facilitate functional analysis of the P. falciparum genome and will help to identify genes with a critical role in parasite progression and multiplication in the human host.

Technical assessment of the affymetrix yeast expression GeneChip YE6100 platform in a heterologous model of genes that confer resistance to antimalarial drugs in yeast

The advent of high-density gene array technology has revolutionized approaches to drug design, development, and characterization. At the laboratory level, the efficient, consistent, and dependable exploitation of this complex technology requires the stringent standardization of protocols and data analysis platforms. The Affymetrix YE6100 expression GeneChip platform was evaluated for its performance in the analysis of both global (6,000 yeast genes) and targeted (three pleiotropic multidrug resistance genes of the ATP binding cassette transporter family) gene expression in a heterologous yeast model system in the presence and absence of the antimalarial drug chloroquine. Critical to the generation of consistent data from this platform are issues involving the preparation of the specimen, use of appropriate controls, accurate assessment of experiment variance, strict adherence to optimized enzymatic and hybridization protocols, and use of sophisticated bioinformatics tools for data analysis.

Organ transplantation: the role of the acute care nurse practitioner across the spectrum of health care

Organ transplantation has become an accepted treatment method for a multitude of conditions once deemed untreatable. Increasing numbers of patients are treated by nurse practitioners before and after transplantation in a variety of settings, such as primary and specialty care clinics, urgent care, critical care units, and long-term care facilities. This article outlines the role of the acute care nurse practitioner in the management of adult transplant recipients in a variety of health care settings and reviews the problems and interventions specific to this patient group. Emphasis is placed on the referral process and collaboration with the transplantation team in patient management.

The role of the transplant advanced practice nurse: a professional and personal evolution

Rapid changes in health care toward cost-effective managed care have resulted in the evolution of the transplant advanced practice nurse to address the care needs of a specific patient population. This article describes the evolution of this role at one institution. The specific responsibilities of the transplant advanced practice nurse are delineated, and phases of development for the experienced clinical nurse specialist entering the role as a novice nurse practitioner are identified and discussed.

Preservation of nucleic acids for polymerase chain reaction after prolonged storage at room temperature

A guanidinium isothiocyanate (GITC) lysis solution was evaluated for its efficacy in preserving nucleic acids for subsequent analysis after prolonged storage at room temperature. Aliquots of thyroid crude cell lysates were stored at 22 degrees C for 8 weeks in the GITC solution. Crude cell lysates stored for 2 weeks in the GITC solution consistently provided adequate RNA and DNA for reverse transcriptase-polymerase chain reaction (RT-PCR) and PCR, respectively, of beta 2-microglobulin, thyroid stimulating hormone receptor (TSHR), and thyroglobulin. Interestingly, the thyroglobulin and TSHR messages from thyroid fine needle aspirate samples were detected by RT-PCR only when stored at room temperature for less than 1 week, whereas the RT-PCR product for beta 2-microglobulin was detectable in 95% of the samples at 3 months. In addition, thyroglobulin DNA was amplified by PCR in nearly all samples stored at 22 degrees C for 2 months. These data suggest that GITC solutions can be used to preserve nucleic acids in most circumstance until transported to laboratories equipped and staffed with appropriate resources.

The use of the polymerase chain reaction to detect bacteria in amniotic fluid in pregnancies complicated by preterm labor

OBJECTIVES

The purpose of this investigation was to determine the feasibility of using the polymerase chain reaction to detect bacteria in amniotic fluid and to compare pregnancy outcomes in subsets of women categorized by amniotic fluid culture, polymerase chain reaction, and interleukin-6 findings.

STUDY DESIGN

Amniotic fluid from 54 pregnancies with preterm labor and no clinical evidence of intraamniotic infection was evaluated with use of the polymerase chain reaction, interleukin-6, and bacterial culture. Gestational age, newborn weight, and time between amniocentesis and delivery were compared between subsets of women categorized by these tests.

RESULTS

With use of the polymerase chain reaction <100 bacteria per milliliter could be detected in amniotic fluid. A total of 55.5% of the amniotic fluid samples were polymerase chain reaction positive, whereas 9.2% of culture results were positive. Birth weights and gestational age at delivery were less and time from amniocentesis to delivery was shorter in the polymerase chain reaction-positive group (p < 0.05). Nine samples (15%) had elevated interleukin-6 concentrations; of these, six were polymerase chain reaction positive.

CONCLUSIONS

The polymerase chain reaction is a sensitive means of detecting bacteria in amniotic fluid. These results provide further evidence of an association between preterm delivery and intraamniotic infection. Not all amniotic fluid samples with elevated interleukin-6 levels have bacteria detectable by the polymerase chain reaction. We anticipate that the polymerase chain reaction will provide another avenue for the detection of bacteria in amniotic fluid.

Who should manage CRRT in the ICU? The nursing viewpoint

Continuous renal replacement therapy (CRRT) is performed in critical care units around the world with various levels of involvement from critical care and nephrology nurses. In this article, factors affecting the delivery of nursing care and the particular expertise nephrology and critical care nurses have in the area of CRRT are examined. Based on this discussion, three proposed models of nursing care for the patient receiving CRRT are discussed: the Nephrology Nursing Model, the Critical Care Model, and the Collaborative Model. Based on related research findings and a comparison of the models, the Collaborative Model is the preferred one, as it brings the highest level of expertise directly to the patient. For the Collaborative Model to work, a framework for collaboration and a high degree of commitment from both specialties must be maintained.